As a violinist, I can say that we call the bow's head "pointe" in French.

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Note added at 2 days3 hrs (2008-10-30 22:03:40 GMT)
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As Arnold said, the horsehair is tied to the wooden part of the head ("pointe" refers to the whole pointy end of the bow) by a ivory/enamel-looking plate. That must be the external (visible) part of the "mortaise" adjustment defended by Arnold. If that's the specific part we're talking about, I never had to hear them for myself as a musician, but I found the terms "plaque de recouvrement" for this particular plate, and "plaque de tête" (the very small flat enamel/ivory-like plate protecting the very point), which suddenly seems to make much more sense than anything else. So finally I think I'd go for "plaque de tête" instead of "pointe" which seems to be way too vague (as Arnold highlighted) and should in fact be used to translate the term "head" just three clicks after. My apologies to all for the confusion.

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Note added at 2 days3 hrs (2008-10-30 22:07:21 GMT)
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I found the specific term "plaque de tête" sur Wikipedia, where I should have been first instead of relying on my lackluster experience in bow terminology. This terms is corroborated by other sources.